Oncothyreon Announces Exercise of Underwriters' Over-Allotment Option and Closing of $54.1 million Public Offering... -- SEATTLE, WA, April 3, 2012

Oncothyreon Announces Exercise of Underwriters' Over-Allotment Option and Closing of $54.1 million Public Offering of Common Stock

SEATTLE, WA, April 3, 2012 /PRNewswire/ - Oncothyreon Inc. (NASDAQ: ONTY) today
announced that it has closed the previously announced underwritten
public offering of 13,512,500 shares of its common stock at a price to
the public of $4.00 per share for gross proceeds of approximately $54.1
million. The shares include 1,762,500 shares of common stock sold
pursuant to the over-allotment option granted by the Company to the
underwriters, which option was exercised in full. The net proceeds from
the sale of the shares, after deducting the underwriters' discounts and
other estimated offering expenses payable by Oncothyreon, will be
approximately $50.3 million.

Oncothyreon currently intends to use the net proceeds of the offering to
fund the development of PX-866, Oncothyreon's irreversible pan-isoform
PI-3 kinase inhibitor, and ONT-10, Oncothyreon's proprietary follow-on
vaccine to Stimuvax. Stimuvax, currently in a Phase 3 pivotal trial,
is a vaccine for patients with non-small cell lung cancer and is
partnered with Merck KGaA. The offering proceeds may also be used for
general corporate purposes.

A shelf registration statement (File # 333-178726) relating to these
securities was filed on December 23, 2011, as amended on January 10,
2012, and declared effective by the Securities and Exchange Commission
on January 10, 2012. A preliminary prospectus supplement related to the
offering was filed with the Securities and Exchange Commission on
March 28, 2012. The securities may be offered only by means of a
prospectus, including a prospectus supplement, forming a part of the
effective registration statement. Copies of the prospectus supplement
and accompanying prospectus relating to the offering may be obtained,
when available, from Cowen and Company, LLC (c/o Broadridge Financial
Services, 1155 Long Island Avenue, Edgewood, NY, 11717, Attn:
Prospectus Department, Phone: 631-274-2806, Fax: 631-254-7140). An
electronic copy of the prospectus supplement and accompanying relating
to the offering is available on the website of the Securities and
Exchange Commission at www.sec.gov.

This press release does not constitute an offer to sell or the
solicitation of offers to buy any securities of Oncothyreon, and shall
not constitute an offer, solicitation or sale of any security in any
state or jurisdiction in which such offer, solicitation or sale would
be unlawful prior to registration or qualification under the securities
laws of any such state or jurisdiction.

About Oncothyreon

Oncothyreon is a biotechnology company specializing in the development
of innovative therapeutic products for the treatment of cancer.

Forward-Looking Statements

In order to provide Oncothyreon's investors with an understanding of our
current intentions and future prospects, this release may contain
statements that are forward-looking. Any statements contained in this
press release that are not statements of historical fact may be deemed
to be forward-looking statements. Words such as "believes,"
"anticipates," "plans," "expects," "will," "intends," "potential,"
"possible" and similar expressions are intended to identify
forward-looking statements. These forward-looking statements include
our expectations regarding future expenses, clinical development
activities, the timing of clinical trial results and the use and
adequacy of cash resources.

Forward-looking statements involve risks and uncertainties related to
our business and the general economic environment, many beyond our
control. These risks, uncertainties and other factors could cause our
actual results to differ materially from those projected in
forward-looking statements, including market risk, the risks associated
with the costs and expenses of developing our product candidates, the
adequacy of financing and cash reserves on hand, changes in general
accounting policies, general economic factors, achievement of the
results we anticipate from clinical trials with our products and our
ability to adequately obtain and protect our intellectual property
rights.

Although we believe that the forward-looking statements contained herein
are reasonable, we can give no assurance that our expectations are
correct. All forward-looking statements are expressly qualified in
their entirety by this cautionary statement. For a detailed
description of our risks and uncertainties, you are encouraged to
review the official corporate documents filed with the securities
regulators in the United States on U.S. EDGAR and in Canada on SEDAR.
Oncothyreon does not undertake any obligation to publicly update its
forward-looking statements based on events or circumstances after the
date hereof.